Whistle



FIG. 1 is a front perspective view of a whistle showing my new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a bottom view thereof; and,

FIG. 6 is a top view thereof.

The broken lines in the drawings depict portions of the whistle that form no part of the claimed design. 

CLAIM The ornamental design for a whistle, as shown and described. 